Sources said the Ibragim Todashev, 27, and Tsarnaev killed the men in Waltham, Mass., after ripping them off for drugs because they did not want the men to later identify them.

Brendan Mess, 25, Raphael Teken, 37, and Eric Weissman, 31, were found with their throats cut in September of 2011. Their bodies were covered with marijuana.

On Tuesday morning, according to officials, a special agent and two Massachusetts State Police troopers were interviewing Todashev regarding his connections to Tsarnaev. Todashev, was originally cooperative, but he was shot after attacking the agent, the FBI said.

"(The FBI) took me and my friend, (Ibragim Todashev). They were talking to us, both of us, right? And they said they need him for a little more, for a couple more hours, and I left, and they told me they’re going to bring him back. They never brought him back," Taramiv said.